Improvement in lifting-jacks



c. F. DAVIS. LIFTING-JACK.

No. 186,315. I Patented Jan. 16, 1877..

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UNITED STATES PATENT OFFICE.

CHARLES F. DAVIS, or WALTHAM, MASSACHUSETTS.

IMPROVEMENT IN LlFTlNG-JACKS.

Specification forming part of Letters Patent No, 186,315, dated January 16, 1877 application filed December 23, 1876.

To all whom it may concern:

Be it known that I, CHARLES F. DAVIS, of Waltham, in the county of Middlesex and State of Massachusetts, have invented an Improvement in Lifting-Jacks, of which the following is a full, clear, and exact description, reference being bad to the accompanying drawings, making part of" this specification, in which- Figure 1 is a perspective view of my im proved lifting-jack. Fig. 2 is a longitudinal vertical section through the center of the same. Fig. 3 is a transverse section on the line :10 a: of Fig. 2. a

My invention has for its object to produce a powerful lifting-jack of simple construction; and consists in a rack-bar sliding vertically on a standard, and operated by a swinging bifurcated lever, pivoted to and supported by links pivoted to the standard, a bolt extending across the end of the lever engaging with the teeth of the rack bar, and a suitable retaining-pawl being employed to hold the rackbar as it is raised by the lever.

To enable others skilled in the art to understand and use my invention, I will proceed to describe the manner in which I have carried it out. n

In the said drawings, A represents the base or foot piece; and B a vertical standard rising therefrom, on which slides the rack bar 0, kept in place thereon by means of straps or (it. Near the top-of this sliding rack-bar G is a horizontal arm, I), which is intended to be placed under theaxle of the wagoit'or other object to be raised, the jack being prevented from slipping out of place by meansot' a projection, c, at the outer end of the arm I). D D are two swinging links, pivoted at their upper ends to the standard B, by means of a bolt,

01, passingthrough it. To the lower ends of these links are pivoted the opposite sides of the bifurcated end of a long lifting-lever, E,

the standard and rack-bar being embraced thereby, a bolt, 0, extending across the open end of the lever and engaging with the teeth of the rack-bar, whereby the latter is raised by depressing the handle of the lever, the rack-bar being retained after each impulse of the lever by a pawl, h, pivoted to the standard B by the bolt 01. p

After each upward movement of the rackbar the lever is swung out, so as to disengage the bolt 0 from the tooth of the rack-bar with which it was in contact, when it is carried down by raising the handle of the lever, to cause the bolt 6 to engage with the next tooth below, and thus take a fresh hold on the rackbar.

The bolt 0 is made removable, in order that the lever may be swung up into a vertical position alongside of the standard A, in which position the jack occupies less space and is rendered more portable.

From the foregoing it will be seen that a jack constructed in accordance with my invention enables the operator to raise a very heavy load with the expenditure of but little power, on account of the great leverage exerted, while the parts are strong and of simple construction.

What I claim as my invention, and desire to secure by Letters Patent, is-

The combination and arrangement of the sliding rack-bar 0, standard B, swinging bifurcated lever E, pivoted to and supported by the links D D, lifting-bolt e, and the retaining-pawl h, constructed and operating substantially in the manner and for the purpose set forth.

Witness my hand this 20th day of Decemher, A. D. 1876.

CHARLES E. DAVIS. In presence of- P. E. TESOHEMAGHER, N. W. STEARNS. 

